Metschnikowia pulcherrima Influences the Expression of Genes Involved in PDH Bypass and Glyceropyruvic Fermentation in Saccharomyces cerevisiae.

Mohand Sadoudi,Raphaëlle Tourdot-Maréchal,Sandrine Rousseaux,Vanessa David,Hervé Alexandre

doi:10.3389/fmicb.2017.01137

Mohand Sadoudi, Raphaëlle Tourdot-Maréchal + Show 3 more

Open Access

https://doi.org/10.3389/fmicb.2017.01137

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Abstract

Previous studies reported that the use of Metschnikowia pulcherrima in sequential culture fermentation with Saccharomyces cerevisiae mainly induced a reduction of volatile acidity in wine. The impact of the presence of this yeast on the metabolic pathway involved in pyruvate dehydrogenase (PDH) bypass and glycerol production in S. cerevisiae has never been investigated. In this work, we compared acetic acid and glycerol production kinetics between pure S. cerevisiae culture and its sequential culture with M. pulcherrima during alcoholic fermentation. In parallel, the expression levels of the principal genes involved in PDH bypass and glyceropyruvic fermentation in S. cerevisiae were investigated. A sequential culture of M. pulcherrima/S. cerevisiae at an inoculation ratio of 10:1 produced 40% less acetic acid than pure S. cerevisiae culture and led to the enhancement of glycerol content (12% higher). High expression levels of pyruvate decarboxylase PDC1 and PDC5, acetaldehyde dehydrogenase ALD6, alcohol dehydrogenase ADH1 and glycerol-3-phosphate dehydrogenase PDC1 genes during the first 3 days of fermentation in sequential culture conditions are highlighted. Despite the complexity of correlating gene expression levels to acetic acid formation kinetics, we demonstrate that the acetic acid production pathway is altered by sequential culture conditions. Moreover, we show for the first time that the entire acetic acid and glycerol metabolic pathway can be modulated in S. cerevisiae by the presence of M. pulcherrima at the beginning of fermentation.

Highlights

Complex interactions between organisms occur when fermentations are conducted with different yeasts (Fleet, 2003; Alexandre et al, 2004; Liu et al, 2015; Albergaria and Arneborg, 2016; Ciani et al, 2016)
The fermentation kinetics of the control S. cerevisiae PB2023 pure culture indicated that the maximal population was reached after 3 days (1.4 × 108 viable cells ml−1)
When the alcoholic fermentation was conducted with sequential culture of M. pulcherrima MCR-24 and S. cerevisiae PB2023, the fermentation progressed to completion in 10 days (Figure 2B)

Summary

Introduction

Complex interactions between organisms occur when fermentations are conducted with different yeasts (Fleet, 2003; Alexandre et al, 2004; Liu et al, 2015; Albergaria and Arneborg, 2016; Ciani et al, 2016). Different studies reported low acetic acid production for certain non-Saccharomyces yeasts (M. pulcherrima, Torulaspora delbrueckii, Starmerella bacillaris) and their capacity in culture with S. cerevisiae to produce lower acetic acid concentrations in comparison to S. cerevisiae monoculture (Bely et al, 2008; Comitini et al, 2011; Milanovic et al, 2012; Rantsiou et al, 2012). These studies suggest that the acetic acid metabolic pathway can be affected by interactions occurring between yeasts, leading to a decrease in the amount of acetic acid. Little is known as yet of the impact of sequential non-Saccharomyces/S. cerevisiae culture on the genes involved in the acetic acid metabolic pathway of S. cerevisiae

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